Gas-motor.



L. A. ABBOTT.

GAS MOTOR. APPLICATION 31mm APBJ, 191a,

Patented Jan. 26, 1915.

2 SHEETS-SHEET 1. Z. 1'19 51 11 194. a 73 Int/en??? Lawrenc 66011 L. A.ABBOTT.

1 GAS MOTOR.

APPLICATION FILED Arlm, 191s.

Patented Jan. 26, 1915.

2 SHEETS-SHEET 2.

LAWitENCE A. ABBOTT, OF CHICAGO, ILLINOIS.

GAS-MOTOR. I

Specification of Letters Patent.

Patented Jan. 26, 1915.

Application filed April 7, 1813. Serial No. 759,451.

To a 'whomit may concern Be it known that I, LAWRENCE A. ABBOTT, acitizen of the United States, residing at Chicago, in the county of Cookand State of Illinois, have invented certain new and useful Improvementsin Gas-Motors, of which the following is a specification.

The present invention relates more particularly to that style of gasmotor known as two cycle.

One of the objects of the invention is to employ an upper piston and alower piston, and to arrange the connections between said pistons andthe crank shaft so as to mini- 'mize the strain excited upon the crankshaft when theexplosive charge is fired.

A further object of the invention is to provide means for admitting afresh charge of explosive mixture to a point between the two pistons.and a further object is to provide means for exhausting the burned gasesfrom between the pistons, and to utilize the pressure of the freshexplosive charge as a means for forcing the burned gases out throughtheexhaust port.

The invention further consists in the features of construction andcombination of parts hereinafter described and claimed.

In the drawings: Figure 1 is a view partly in section, and of asemi-diagrammatical nature, showing the position of the pistons and theposition of the connecting rods between the pistons and crank shaft at,or approximately at, the commencement of the driving stroke; Fig. 2 aview similar to Fig. 1 showing the position of the parts after the crankhas been turned a quarter revolution; Fig. 3 a view similar to Fig. 1showing the position of the parts when the crank has turned a halfrevolution; Fig. 4 a view similar to Fig. 1 showing the position of theparts when the crank has been turned a three quarter revolution; Fig. 5a vertical section of the engine of the present invention; Fig. 6 asection on line 66 of Fig. 4 looking in the direction of the arrow; Fig.7 a section on line 77 of'Fig. 4 looking in the direction of the arrow;and Fig. 8 a curve chart showing the movements of the two pistons, andshowing the relation between the pistons at the time of opening andclosing the exhaust and opening and closing the intake.

The present invention, as heretofore stated, relates more particularlyto that type of gas motor known as the two cycle; that is one in which afresh explosive mixture is drawn in and fired upon each completerevolution of the crank shaft.

The present invention utilizes two pistons. an upper one and a lower oneand arranges the connections between these pistons and the crank shaftso that when the explosive mixture is fired one of the pistons will pushupon the crank shaft and the other pull, the force of both of thepistons being exerted toward moving the crank shaft in a commondirection, but the combined push and pull will equalize the strain towhich the crank shaft would be otherwise subjected to,

and thus eliminate at least to all practical purposes, the wear and tearincidental to the strain placed on the crank shaft by the violentimpetus given to the pistons when the explosive mixture is fired.

Referring now to the drawings, and more particularly to Fig. 5, in whichthe structure is illustrated more in detail, the motor as illustrated,comprises a cylinder or casing 8, which if desired, may be extended soas to form a housing or casing 9 for the crank, although this portion ofthe structure may be varied in accordance with the ideas of the builder.The casing is also formed so as to provide a-water chamber 10 forcooling purposes, and attached to the upper end of the casing is amixture box 11 provided with an air inlet 12, into which box enters avvapor supply pipe 13. The combining of air and vapor to produce theexplosive mixture takes place within this box. Communication between theupper end of the cylinder and this box is controlled by means of a valve14;, opening downwardly, and maintained in normal seated positionthrough the instrumentalities of a spring 15, and the upper end of thecylinder is enlarged, as for instance by providing a series of grooves16, the purpose of which will be more clearly hereinafter explained.

Moving within the cylinder 8 is an upper piston 17 and a lower piston18. The upper piston, as illustrated, comprises a head 19 from whichdepends a tubular sleeve like member 20, and the lower piston 18 isarranged to travel within said sleeve 20 so that this second pistonfinds its bearing within.

the chambered,portion of the upper piston. The upper piston is providedwith a connecting rod 21 depending from the lower portion of the sleeve20, and this rod is com nected to the crank shaft, as at 22. The

lower piston is provided with a connecting rod 23 which is connected tothe shaft as at 21. By referring to Figs. 1 to 5 inclusive it will beseen that these connections are spaced apart approximately one quarterof the distance of the circle described by a revolution of the crankshaft, and that at the time of firing, or near the time of firing, theupper piston is at its lowermost position and the lower piston midwaybetween its highest and lowest positions.

Now taking the parts in the position shown in Fig. 1 or 5 and supposingthe circuit is established at this time which creates the spark thatfires the explosive mix ture. The first quarter movement of the crankshaft moves the parts from the position shown in Fig. 1 into theposition shown in Fig. 2, and assuming the lower end of the connectingrod 23 of the lower piston to be at A, and the connecting rod 21 of theupper piston to be at B at the commencement of the stroke, the firstquarter movement will move the lower end of the connecting rod of theupper piston from B to (1, and the lower end of the connecting rod ofthe lower piston from A to B. The connecting rod 21 of the upper pistonwhen moved from B to C will exert a pull upon the crank and theconnecting rod 23 of the lower piston moving from A to B will exert apush on the crank. This combined push andpull communicated to the crankshaft upon the firing of the explosive mixture, will serve to minimizethe effect of the shock and jolt which would otherwise be communicatedto the crank shaft upon the initial movement of the driving parts of themotor, after the explosion has taken place. By comparing Figs.- 1. and 2it will be seen that upon this initial movement the upper piston willtravel'upward and the lower piston downward as would be natural in caseP of a "sudden expansion of gas between the pistons. Now referring to F1g.j3 where the next movement of the parts is illustrated it will beseen that the connecting rod 21 is moved from the-point C to the point Dand the connecting rod '23 has moved from the point B to the point C andby referring to the curve illustrating the. relative movements of thepistons it will be observed that during this stroke the upper pistonwill travel at an increased speed to the lower piston.- 'In the movementfrom the position shown in Fig. 2 to that shown in Fig. 3, the pistonsare traveling in the samedirection, both of them being on theirupstroke, but ,as heretefore explained the upper piston during-suchmovementis traveling at an'increased speed to the lower-- piston.

Nowreferringto Fig. 4 in which the next position of the'parts' isillustrated when the crank shaft has been turned a three quarterrevolution, it will be seen that the connecting rod 21 will havetraveled from the point D 'to'the point A, and that the connecting rod23 will have traveled from the point C to the point D. During thismovement the pistons will again travel in opposite directions, the upperpiston downward and the lower piston upward, with the lower pistontraveling at an increased speech The foregoing describes the variouspositions assumed by the parts during a quarter, half, and threequarters revolution of the crank shaft. To obtain the final quarter ofthe revolution the connecting rod 21 is moved from A to B, andconnecting rod 23 from D to A bringing the parts back to the positionshown in Fig. 1.

The upper piston 17 is provided with a cross passage 25 which is formed,in the construction shown, by making the piston of two pieces, joiningthe same together, and spacing them apart by means of washers 26, but ofcourse this precise construction may be varied. Communication betweenthe cross passage and the under face of the piston is controlled by acheck valve 27, opening downward, and normally held in seated positionby a spring 28, this may be termed the intake for the explosive mixture.In the construction illustrated the casing is provided with a chamber 29from which leads an exhaust pipe 30, and the sleeve 20 of the upperpiston is provided with a series of ports or openings31. These portsserve to. establish communication between the chamber 29 and the spacebetween the pistons 17 and 18 when the burned gases are exhausted. x f

The operation of admitting the .fresh explosive mixture and exhaustingthe burned gases will now be explained. Whenv the arts move from theposition shown in Fig. 1 to the position shown in Fig. 2 it will beunderstood that by reason of the travel of the pistons in oppositedirections the ports 31 will be brought above the top of the lowerpiston 18 and communication thus established between the space betweenthe piston and the discharge chamber 29. Still referring to Fig. 2 itwill be noted that the passage 25 has not yet been brought intocommunication with the grooves 16 and so the fresh. chargprfiofexplosive mixture has 'fresh supply of mixture which is lying above theupper piston, and upon the upward stroke of the upper piston the valve14 has been closed, and the explosive charge .previously admitted isbeing compressed between the upper face of the upper piston and the topof the cylinder. @Shortly after communication between the ports '31 andthe discharge chamber 29 is established, the

cross passage 25 is brought into communication with the grooves 16 andthe compressed fresh mixture will flow through this cross passage,unseatingwthe valve 27,- and entering into the space tween the pistons.The action of this mixture entering under pressure will force the burnedgases out through the discharge passage. By referrin to Figs. 2 and 3 itwill be seen that b0 the lower piston and the upper piston will betraveling upward, during a quarter revolution of the crank shaft whichmoves the parts from the positionshownin Fig. 2 to the position shown inFig. 3, and during this quarter revolution of the crank shaftcommunication will be constantly established between the space betweenthe pistons and the exhaust passage, and further- .more', during thisstroke, the fresh explosive mixture will be constantly entering thespace between the pistons under pressure, and will force the burnedgases out through said discharge passage. Duringthe next stroke whichmoves the parts from the position shown in Fig. 3 to that shown in Fig.4 the pistons will move in opposite directions, the upper pistondownward and the lower piston upward. At the com mencement of thisstroke the lower piston will operate to close communication between thespaces between the pistons and the exhaust passage by reason of itspassing over and blocking communication through the ports 31, so thatduring this stroke the resh explosive charge will be compressed betweenthe pistons, when the fresh charge between the pistons has beencompressed to a point to create a pressure stronger than the pressure ofthe fresh mixture above the upper piston, the valve 27 will close, and afurther inlet of explosive mixture between the pistons prevented. Atsome time during this movement of the pistons in opposite direction,either when the pistons are at their closest relativeposition, or atsome period during the final quarter movement of the crank shaft, thecharge will be fired so that the expansion of the highly compressedmixture will give the maximum efiiciency or power to the subsequentstroke.

It is believed that the operation of the parts will be understood fromthe fore going, and especially so in view of the following explanationof the curve chart: Assuming that the line 32 on said chart representsthe different positions of the lower piston 18, the line 33 representsthe different positions of the upper piston; the line 34 represents thedifferent positions of the ports 31; the line 35 represents thedifferent positions of the passage 25; the line 36 represents thegrooves 16 and the line 37 represents the exhaust chamber 29. Then uponmovement of the parts from the posifirst established at the point 41.The passage will be brought into communication with the groove 16 at thepoint 42, and it will thus be seen that the exhaust is open a short timebefore the intake.

. In traveling from the position shown in Fig. 3 the upper piston willhave traveled from the point 38 to the point 43, and the lower pistonfrom the point 39 to the point 44-, both traveling in the same generaldirection, although the upper piston is traveling at a somewhatincreased speed. The

point 45 represents the point at which the.

lower cylinder acts to close the ports 31, and the point 46 indicatesthe point where the passage 25 is brought out of communication with thegroove 16, cutting ofi the intake of fresh fuel. From this it will beseen that the exhaust closes before the intake.

- In traveling from the position shown in Fig. 3 to that shown in Fig. 4the upper piston will travel from the point 43 to the point 47, and thelower piston will travel from the point 44 to the point 48, both pistonstraveling in opposite directions and compressing the fresh mixture.between the pistons. Then in traveling fromthe position shown in Fig. 4back to the position shown in Fig. 1 the upper piston will travel fromthe point 47 to the point 49, and the lower piston from the point 48 tothe point 50, and at some time during this movement the fresh charge isfired. It would be advisable to fire the charge at about the time whenthe upper piston has reached the point 51 and the lower piston the point52, at which time the pistons are in closest position to one another,and the greatest compression of the mixture is obtained, the particulartime of firing, however, can be arranged according to the desire of themanufacturer or operator, but should be during the period of movement ofthe parts from the position shown in Fig. 4 to that shown in Fig. 1.

By referring to the drawings it will be seen that the points ofengagement between the connecting rod and the crank shaft are spacedapart approximately a quarter of the distance of the circle described bythe crank shaft during a revolution. As illustrated in the drawings, theconnecting rods are eccentrically attached to a series of disks 53,butof course a crank shaft of other suitable formation may be used in placethereof,

, by utilizing the disks, however, the element of a fly wheel isprovided for without using a separate member for this purpose.

Referring now to Fig. 5 it will be seen that the connecting rod 23 is atits greatest angularity with respect to the pistons and that theconnecting rod 21 is at a position of approximate parallelism withrespect to the pistons. I am of the opinion that if the impetus is givento the connecting rod when said rod is at the point of greatestaugularity with respect to the piston, a greater power will betransmitted to the crank shaft. Then when such impetus is given to theconnecting rod when it is in a position of parallelism or approximatelyso with the pistons. Thus as the connecting rod 23 descends, the degreeof angularity between this rod and the pistons will be reduced, and asthe connecting rod 2-1 moves upward, the angularity of this rod withrespect to the pistons will be increased, so the power transmittedthrough the medium of the connecting rod 23 decreases, the powertransmitted through the medium of the connecting rod 21 increases duringthe first quarter movement and thus full power is obtained by thecombined movements of the two connecting rods in the manner abovedescribed. This fact will also be true in each quarter of astroke,although as to whether the rod 21 for instance would decrease orincrease as the stroke progressed, would depend on the position of thepistons,-but the fact remains that ,on each quarter stroke, one of therods increases its angularity thus maintaining power throughout.

A spark plug 54 is shown in the drawings which, when suitably connectedconstitutes an ordinary jump spark firing mechanism, and is operated atsuitable intervals, in the ordinary and Well known manner, to fire theexplosive charge.

I claim:

In a gas motor, the combination of a cyl inder, an outer hollow pistonwithin said cylinder, an inner piston traveling within the chamberedportion of said outer piston, a crank shaft, a link connecting the outerpiston and crank shaft, a link connecting the inner piston andcrankshaft, the points of connection of the links with the crank shaftbeing a distance apart equal to a quarter revolution of said shaft, avalve inlet at the top of said outer piston for the admission of anexplosive charge to the space between the pistons, an exhaust for theburnt gases controlled by the relative positions of said pistons, meansfor firing the explosive charge admitted'between the pistons while thepistons are in close proximity and the charge under compression, andsaid explosion occurring when the crank shaft has reached orapproximately reached the end of its first quarter strokes.

LAWRENCE A. ABBOTT.

Witnesses: WM. I. BOND, EPHRAIM BANNIXG.

